1. Field of the Invention
This invention relates to a method and apparatus for recognizing a region corresponding to an image storage sheet, which region is embedded in a read-out image. This invention also relates to an image processing method and apparatus for performing predetermined image processing on an image in the region having been recognized with the method of recognizing a region corresponding to an image storage sheet. This invention further relates to an apparatus for reading out an image from an image storage sheet, which apparatus is utilized for carrying out the method of recognizing a region corresponding to an image storage sheet. This invention still further relates to a platen cover and a sheet for a platen cover for use in the apparatus for reading out an image from an image storage sheet. This invention also relates to a recording medium, on which a program for causing a computer to execute the method of recognizing a region corresponding to an image storage sheet has been recorded and from which the computer is capable of reading the program.
2. Description of the Related Art
With the enhancement of performance of various digital printers and the reduction in cost of the digital printers made in recent years, there has arisen a tendency toward increased use of operations for reading out images, such as color images on color photoprints, which are formed with silver halide photographic materials, or images on color image storage sheets containing color images, with scanners (which are examples of apparatuses for reading out an image from an image storage sheet), and forming images in albums, or the like.
There have heretofore been proposed image processing techniques wherein, in cases where a plurality of different image storage sheets containing color images (e.g., color photoprints) are placed on a platen (i.e., an image storage sheet support base) and covered with a platen cover during an image read-out operation, the plurality of the images on the image storage sheets are read out with one time of scanning operation, thereafter positions, shapes, rotation angles, and the like, of the respective images are recognized automatically and corrected, and predetermined image processing is then performed.
One of image processing methods for the image processing techniques described above has been disclosed in, for example, Japanese Unexamined Patent Publication No. 10(1998)-222688. The disclosed image processing method comprises the steps of discriminating image objects (corresponding to areas of photoprints) in an input image, modeling a shape, which expresses each of boundaries of the image objects, into a predetermined shape, and characterizing the objects.
However, with the image processing method disclosed in Japanese Unexamined Patent Publication No. 10(1998)-222688, wherein the image objects are discriminated, the problems often occur in that, in cases where an image is read out from an image storage sheet containing a color image, error occurs with the discrimination of the region corresponding to the boundary of the image storage sheet.
In order for the error occurring with discrimination of the region corresponding to the boundary of the image storage sheet to be eliminated, it may be considered to utilize one of various known techniques for discriminating the boundary and the size of the object (i.e., the image storage sheet), from which the image has been read out with a scanner, or the like.
For example, methods of detecting a size of an image storage sheet by blackening an image storage sheet pushing surface of a platen cover of a scanner have been disclosed in, for example, Japanese Unexamined Patent Publication Nos. 5(1993)-130337 and 5(1993)-134329. Also, a method of detecting a size of an image storage sheet by making an image storage sheet pushing surface of a platen cover whiter or more black than the image storage sheet has been disclosed in, for example, Japanese Unexamined Patent Publication No. Japanese Unexamined Patent Publication No. 56(1981)-105579.
Further, methods of utilizing coloring agents on an image storage sheet pushing surface of a platen cover have been disclosed in, for example, Japanese Unexamined Patent Publication Nos. 56(1981)-22424, 56(1981)-62274, and 2(1990)-131662.
Furthermore, a method of detecting a size of an image storage sheet by forming a yellow area and a white area on an image storage sheet pushing surface of a platen cover has been disclosed in, for example, Japanese Unexamined Patent Publication No. 5(1993)-122466.
The aforesaid methods of detecting a size of an image storage sheet, wherein the image storage sheet pushing surface of the platen cover is colored (with a chromatic color or an achromatic color), is efficient for document image storage sheets whose substrates are white. However, the aforesaid methods of detecting a size of an image storage sheet have the problems in that, in cases where images are read out from image storage sheets containing color images having various colors, such as color photoprints, the color of the platen cover often coincides with the color at a certain area of the color image, and therefore error often occurs with the recognition of the region corresponding to the image storage sheet.
Accordingly, methods of detecting a region corresponding to an image storage sheet appropriately regardless of whether the image storage sheet contains or does not contain a color image have been proposed in, for example, Japanese Unexamined Patent Publication Nos. 8(1996)-139848, 10(1998)-177331, and 11(1999)-24185. With the methods proposed in Japanese Unexamined Patent Publication Nos. 8(1996)-139848, 10(1998)-177331, a light absorbing agent for absorbing light, which has wavelengths falling within a predetermined wavelength region in a non-visible region, is applied onto an image storage sheet pushing surface of a platen cover. With the method proposed in Japanese Unexamined Patent Publication No. 11(1999)-24185, a transparent fluorescent coating material for producing infrared fluorescence is applied onto an image storage sheet pushing surface of a platen cover. However, the proposed methods of detecting a region corresponding to an image storage sheet have the problems in that a detector for detecting light of the non-visible region, such as an infrared region, must be provided besides a detector for image readout, and therefore the cost cannot be kept low.
A method of detecting a region corresponding to an image storage sheet, wherein a regular pattern, such as a dot pattern of red, green, and blue three primary color dots having a diameter of, e.g., 0.2 mm to 5 mm, is periodically formed in a main scanning direction and a sub-scanning direction on an image storage sheet pushing surface of a platen cover, has been proposed in, for example, Japanese Unexamined Patent Publication No. 5(1993)-110779. However, with the proposed method of detecting a region corresponding to an image storage sheet, wherein the dot pattern is utilized, colors of pixels located between adjacent dots cannot be discriminated, and therefore there is the risk that error will occur in recognition when a peripheral edge area of the image storage sheet is detected or when a slight space between adjacent image storage sheets is detected.